JP6863693B2 - Graphics processing system and method - Google Patents

Description

The present invention relates to a graphics processing system, and more particularly to drawing an image using a smooth shape such as a smooth curve in a graphics processing system.

It is increasingly desired to be able to draw smooth shapes for effective and accurate display in a particular shape defined by a smooth curve (having a smooth curve as its edge or boundary) in a graphics processing system. .. Generally, a shape having a continuous edge or boundary curve and the first derivative of the curve being segmentally continuous is considered to be a smooth shape (a shape defined by the smooth curve) from the viewpoint of graphics processing. (For the purposes of the present invention and the present application, it is considered to be a smooth shape and correspondingly a smooth curve). Examples of such smooth curves in graphics processing are Bezier curves, spline curves and arcs.

In recent years, it has become more and more common to use vector graphics in computer graphics. As is known, one major advantage of vector graphics over raster graphics in the industry is the ability to provide resolution-independent images, i.e., images that can be magnified indefinitely without degradation. For example, independent characters (glyphs) in computer fonts such as TrueType® are generally stored as vector images.

Vector graphics are generally based on the use of independently defined geometric objects and are generally one or more line segments connected together at anchor points to form a path, such as a straight line or (two). It is described by a curve (such as a Bezier) curve, an elliptical arc, or a cubic (eg Bezier) curve.

Vector graphics objects / paths are defined and manipulated in a space commonly referred to as "world space". However, in order to output the object / path of the vector graphics to a video display or printer, the object / path defined in the world space is in a suitable form to be displayed on the screen or output to the printer. Need to be converted to. The transformation generally projects an object / path defined in world space into another space, commonly referred to as "surface space", that corresponds to the viewpoint (geometry) of the output display to which the object / path is referenced. including. The transformation between world space and surface space is commonly referred to as "world surface transformation".

Once the objects / paths in the vector graphics have been converted to a surface space representation, they are then drawn. It may use a pre-computed representation of the object and / or route.

One way to transform a vector graphics object / path into a pre-computed representation that can be used to draw an object or path, for example in surface space, is to use a signed distance field stored in the texture. Is to use. The distance field can then be sampled when drawing the object. A signed distance field contains an array of points, such as texels, whereas the closest distance to the path or edge of the object is stored point by point, with the distance sign being inside the object to be drawn by that point. Indicates whether it is in or outside. Therefore, by sampling the signed distance field, it is determined whether the sample point is inside or outside the object to be drawn.

Signed distance fields assist in drawing such objects, such as font glyphs, and allow the use of techniques such as antialiasing. However, for example, the calculation of a signed distance field from an object / path in vector graphics using scanline rasterization is complicated. Also, if the object or path needs to be expanded, the signed distance field may only be stored at a limited resolution, so the signed distance field is recalculated at the new resolution. It may be necessary to do so. In addition, when drawing more complex objects, such as font glyphs that can contain multiple curved segments, the use of signed distances is due, for example, to artifacts in the methods used to calculate signed distance fields. It has been found to result in loss of detail in drawn objects, such as smoothing sharp corners. Therefore, it is computationally expensive to calculate this in real time, or a large amount of space is required to store the pre-calculated signed distance field offline. This can introduce delays in drawing such objects / paths and may be desirable to do in real time, for example for dynamic web pages.

Applicants therefore consider that there is room for improved techniques and systems for drawing smooth curves and shapes defined by smooth curves.

Seen from the first aspect, the present invention provides a method of generating a rendered output using an input curve in a graphics processing system. The method is
For the input curve defined in world space
Steps to determine the part of the standard curve defined in the standard space corresponding to the input curve and the transformations required to map the input curve to part of the standard curve,
For each of the multiple sample points in the world space surrounding the input curve
Convert the sample point from world space to standard space using the determined transformation between world space and standard space.
In standard space, determine the point on the determined part of the standard curve that is closest to the transformed sample point.
Thereby, for each of the transformed sample points in the standard space surrounding the standard curve, the step of determining the corresponding closest point on the standard curve in the standard space, and
When generating the rendered output, it includes a step of using the determined closest point on the standard curve with respect to the transformed sample point in standard space.

When viewed from the second aspect, the present invention provides a graphics processing system for producing a rendered output using an input curve. Graphics processing system
For the input curve defined in world space
Determine the part of the standard curve defined in the standard space corresponding to the input curve and the transformations required to map the input curve to part of the standard curve.
For each of the multiple sample points in the world space surrounding the input curve
Convert the sample point from world space to standard space using the determined transformation between world space and standard space.
In standard space, determine the point on the determined part of the standard curve that is closest to the transformed sample point.
Thereby, for each of the transformed sample points in the standard space surrounding the standard curve, a processing circuit configured to determine the corresponding closest point on the standard curve in the standard space.
With a processing circuit configured to use the determined closest point on the standard curve with respect to the transformed sample point in standard space when generating the rendered output.
To be equipped.

In the present invention, the rendered output first takes the input curve defined in "world space" (which is flat and therefore may have only two dimensions, or may be three-dimensional space) into "standard space". Is generated using the input curve by mapping to the corresponding predefined "standard" curve defined within. Positions in standard space are then transformed from their corresponding positions in world space surrounding the input curve and sampled (tested) to determine the points on the standard curve that are closest to each of the sampling positions. These closest points are used to produce the rendered output. Use that information to draw glyphs for shapes where the input curves form at least part of those outlines, such as fonts, or based on objects where the input curves form at least part of those outlines. Can draw lighting or shadows.

However, the applicant may use only, for example, rotation, transformation and uniform expansion for at least a portion of a predefined single curve or fundamental curve, referred to herein as a "standard curve". We recognize that we can transform all curves in a curve family.

Thereby, therefore, to determine information about a single curve, i.e. a standard curve, about one or more input curves used by the graphics processing system to be used in generating the rendered output. Can be used. In other words, for example, you do not have to derive or store data in association with each independent input curve to be drawn used by the graphics processing system, but simply derive or store data about the standard curve. Good. The data can then be used to generate rendered output with each of the independent input curves belonging to the family (set) of input curves represented by the "standard curve".

Therefore, the present invention not only provides a more efficient mechanism for generating rendered output using one or more input curves, but also provides a particularly convenient mechanism for doing so. For example, once a standard curve in standard space is defined, points on that curve can be referenced simply by a single coordinate, eg, the x coordinate (thus they can be used in calculations). May be. Therefore, the standard curve is used to determine the point on the curve that is closest to the sample point, and then the point is used to determine the distance to the closest point on the curve (part of the information in the signed distance field). It can, for example, hold a mathematical representation of the input curve defined using vector graphics. This is a simpler and more accurate way to determine the information that increases the speed and accuracy of generating rendered output using the input curve. This is compared to techniques using signed distance fields that are evaluated using scanline rasterization, which leads to loss of information when calculating signed distance fields, and therefore details in the rendered output. It leads to the loss of.

Providing a simpler process for generating rendered output using such input curves helps reduce the processing and power load of the device running the process and cannot implement battery-powered and multifunctional processing. It may be possible to use it in simpler devices such as mobile and wearable devices. Alternatively, the increased efficiency of the process allows more sophisticated rendering functions to be performed without the associated increase in processing and power load associated with the device compared to previous techniques, or the required information (eg, for example). The points on the standard curve closest to each of the transformed sample points) can be (re) calculated in real time as needed.

A simpler and more accurate process (eg, analytical calculation of points on the standard curve closest to the transformed sample point) is used when using such input curves, especially for the generation of rendered output when drawing fonts. This allows the font to be presented more attractively to the display, especially when the text is magnified so that the font may need to be recalculated.

Input curves used by the processes of the invention and defined in world space, eg, input to the processes of the invention, are first defined by applications that require, for example, to generate rendered output using the input curves. It may be an input curve. However, it is also possible that the input curve is a curve derived from another curve defined in world space. It is also considered, for example, that the input curve may be derived by transforming another curve or initial curve, eg, from another space it receives in it to world space, according to the present invention. ..

The input curve may be input to the graphics processing system in any suitable and desired manner. For example, the input curve may be stored (in advance) in the graphics processing system and read from the stored position, or the input curve may be determined by the graphics processing system itself. In another embodiment, the input curve may be more aggressively input by an application that requires, for example, to generate a rendered output using the input curve. In a preferred embodiment, the method comprises the step of receiving an input curve (and the processing circuit is so configured).

A single definition for, for example, a rendered output containing a shape drawn using an input curve, eg, for the entire length (or at least a portion of that length used to generate the rendered output). It may be generated using only a single curve with (eg, mathematical formula). It is preferable that the input curve has a form capable of deriving a "standard curve" having the above-mentioned properties. Therefore, the input curve used by the graphics processing system may be any curve from a family of curves that may have suitable relevant standard curves.

One family of curves that can have relevant standard curves of this form are quadratic curves. In this case, the standard curve can be a basic quadratic curve, i.e. a curve of the form ^{y = x 2.} Therefore, in a particularly preferred embodiment, the input curve in world space received by the graphics processing system is a quadratic curve.

It is equally considered that the rendered output may be generated using multiple input curves, eg, using multiple curve segments, each with a different definition (eg, a mathematical formula) on their length. ing. For example, a glyph for a font is generally defined by a plurality of curved segments (which may include linear segments) that together form an outline of the glyph.

Or or instead, the input curve does not have to have a corresponding curve in standard space, so the initial curve is the corresponding standard curve (which is a member of a family of curves with associated standard curves). It may be subdivided into multiple curve sections of the segment it has, eg, the input curve used in the rendered output differs from the initial curve defined in world space (eg, along the length of the initial curve). It may be derived by subdividing into two or more separate input curves (defined as separate input curves for the section). For example, a cubic curve or an elliptical curve may be subdivided into a plurality of quadratic curves. This allows the invention to be used to draw curves that may not have a direct corresponding standard curve that is directly defined (and / or stored) or available.

In these embodiments, the method may include subdividing the initial curve defined in world space into multiple input curves (and the processing circuit may be configured as such), or the input curves. One or more of these are then processed respectively to produce a rendered output in the manner of the invention. For some initially defined curves, eg cubic Bezier curves, when subdividing the initial curve into multiple input curves, the multiple input curves that best fit the initial curve, eg, quadratic Bezier curves, Part of the calculation may be reused (and therefore the processing circuit may be configured to do this) for discovery. For example, a secondary Bezier is defined by its start and end points, and its gradient (which can be defined by a third control point). These parameters can then be compared, for example, with the corresponding parameters for standard adjacent Beziers to determine if they can be merged.

In a preferred set of embodiments, when generating rendered output with multiple input curves, the method of the invention is repeated for each of the input curves (eg, segments), eg, each input curve (segment). ) Is converted to standard space. In standard space, for each of a plurality of sample points in the world space surrounding the input curve (segment), a point on the determined portion of the standard curve closest to the transformed sample point is determined. It then returns, for each transformed sample point, the closest determined point on the standard curve (segment) to the array of transformed sample points surrounding each of the multiple standard curves, and then back. , These determined closest points can be used when generating the rendered output.

Applicants compare complex shapes, such as fonts, with input curves that are actually few, but not all, in one of a few curve families that may be desired to be used when producing rendered output. We recognize that we can draw with a small number of input curves, eg, represent most, if not all, of the curves that we may want to define. The input curve may be any suitable curve. The input curve is preferably a smooth curve. The smooth curve or each smooth curve is preferably a curve that is continuous and the first derivative of the curve (in the path of the curve) is segmentally continuous. The input curve is preferably a straight line, (eg, quadratic or cubic) Bezier curve, spline curve and / or (eg, elliptical) arc.

However, as described further below, the input curve may include more complex curves such as ellipses and / or hyperbolas, even if the curve does not need to be subdivided into, for example, multiple quadratic curves. Good. However, there is no unique (in two-dimensional) transformation from world space to standard space for an input curve defined in this way, so the definition of the curve is, for example, the eccentricity of the curve, for example. It may be necessary to include more information represented as three dimensions in standard space. This may be stored as part of the definition of the input curve, or when the input curve contains an ellipse or a hyperbola, the method may include a step of determining the eccentricity of the input curve (and the processing circuit). It may be configured that way).

When the input curve contains ellipses and hyperbolas along with the quadratic curve, for example, this provides the user with a useful toolbox for defining the complex shapes used when producing rendered output, for example. One or more input curves can be converted to the corresponding standard curves only by rotation, enlargement and conversion, which are relatively hardware friendly.

Input curves used by the processes of the invention and defined in world space, eg, received as inputs to the processes of the invention, may be defined in any desired and appropriate manner. For example, it is preferred that the graphics processing system be able to receive information that defines the input curve, such as the position of the curve and any parameters associated with the curve. The input curve has a fixed length, eg, part of the shape and thus preferably as a definition of the input curve, and is therefore used by a graphics processing system, eg, the information received preferably includes an end point of the input curve. Since the input curve can be converted to the corresponding standard curve using only rotation, transformation and uniform expansion, this is the standard curve corresponding to the input curve, such as its start and end points, as described further below. A portion of can be easily determined during use.

The input curve is generally a start point, an end point, and the position of multiple control points in world space, including one or more intermediate points, along with an indication of the type of curve drawn between the start and end control points. It is preferred to be defined. For example, preferably, as described above, the input curve is a straight line, a quadratic Bezier curve (requiring a single intermediate control point), a cubic Bezier curve (requiring two intermediate control points), a spline curve. And one of the arcs (eg, elliptical or hyperbolic). The definition of the input curve may also include, for example, the slope of the curve at one or more of the control points. For example, a quadratic Bezier curve may be defined by three control points, or by a gradient at two (end) control points and these two control points.

Therefore, it is preferable that the definition of the input curve includes a plurality of control points in the world space and information indicating the type of the curve. Also, when the input curve is received by the graphics processing system, the step of receiving the input curve defined in world space receives information indicating the position of multiple control points in world space and the type of curve. It is preferable that the processing circuit includes (and the processing circuit is configured as such).

For the input curve used to generate the rendered output, for example, when the input curve is received by a graphics processing system, it can determine the corresponding part of the standard curve in the standard space that represents the input curve. is necessary. The decision may be made in any suitable and desired manner.

In a preferred embodiment, this is done by taking the input curve defined in world space and determining the transformations required to place it in the corresponding portion of the standard curve in standard space. As mentioned above, the transformation (world standard transformation) should only require rotation, transformation and / or uniform expansion. Therefore, it is preferable that the step of determining the transformation that transforms the input curve in world space onto the appropriate portion of the standard curve, if any, includes the step of determining the rotational component of the transformation (and the processing circuit). It is preferably configured to do so).

The rotational component of the conversion may be determined by any suitable desired method. In a preferred embodiment, however, again, when the input curve in world space (and thus the standard curve in standard space) is a quadratic curve, the rotational component of the transformation makes the axis of symmetry of the input curve in standard space. It is determined by determining the rotation required to be parallel to the axis of symmetry of the standard curve of. The rotation therefore aligns the axis of symmetry of the input curve with the direction of the axis of symmetry of the standard curve (eg, the y-axis in standard space).

Similarly, the step of determining the transformation that transforms the input curve in world space onto the appropriate portion of the standard curve in standard space preferably includes (and, if any, the step of determining the transform component of the transformation. , It is preferable that the processing circuit is configured as such).

The conversion component of the conversion may be determined by any suitable desired method. However, in a preferred embodiment, when the input curve (and thus the standard curve) is a quadratic curve, the transform component of the transformation is the top of the input curve of the input curve in world space, the standard curve in standard space. It is determined by determining the transformation required to move to the top of the sky, eg the origin of standard space. Therefore, it is preferable that the step of determining the conversion component of the transformation, if necessary, follows the step of the rotation component of the transformation, if necessary.

Therefore, in a preferred embodiment, the step of determining the transformation component of the transformation comprises determining the transformation required to map the nadir of the input curve to the nadir of the standard curve in standard space (and). , The processing circuit is preferably configured to do so).

It is preferable that the step of determining the transformation that transforms the input curve in world space on the appropriate portion of the standard curve also includes, if any, the step of determining the uniform expansion component of the transformation (and the processing circuit). Is preferably configured to do so).

The uniform expansion component of the conversion can also be determined in any suitable and desired manner. However, in a preferred embodiment, again, when the input curve in world space (and thus the standard curve in standard space) is a quadratic curve, the uniform expansion component of the transformation is, for example, rotated and / or transformed. It is determined by determining the expansion factors required to expand the input curve to the standard curve, for example, by testing the quadratic form of the input curve.

The steps of rotating, transforming and determining the uniform expansion component of the transformation can be carried out in any order as needed. However, in a preferred embodiment of the invention, the rotating component is first determined, then the conversion component is determined, and finally the uniform expanding component is determined.

When the input curve has a fixed length, for example defined by the start and end points, the input curve is determined when the transformation required to map the input curve in world space to the standard curve in standard space is determined. It is preferred that a portion of the standard curve corresponding to is determined using the determined transformation to determine two positions on the standard curve corresponding to the start and end points of the center curve of the input curve. This then gives the position of the input curve in standard space.

When the standard curve in the standard space corresponding to the input curve in the world space is determined, and therefore the conversion from the world space to the standard space is also determined for the input curve, multiple in the world space surrounding the input curve. Each of the sample points can be transformed into a corresponding point in standard space using the same transformation (independently or together).

Multiple sample points surrounding the input curve, for example, at a level of sufficient resolution for the level of detail at which the rendered output should be drawn (or cover the most expected magnification level of the rendered output produced). It may be selected in any suitable and desired manner so as to provide the determined closest point on the input curve. Alternatively, if it is desirable to determine the closest point on the input curve at low resolution, eg, for a small number of sample points, and then later, if necessary, for example, produce the rendered output at an enlarged level. It may be determined in high resolution (ie, in more detail). In one embodiment, a bounding box surrounding the input curve is drawn, in which a plurality of sample points surrounding the input curve are defined.

In one embodiment, the closest points on the standard curve are used for all sample points surrounding the input curve for which information related to the input curve is ultimately determined for use when generating the rendered output. It does not have to be decided. For example, without having to convert the information determined for each of the additional sample points into standard space for each of these additional sample points to determine the closest point on the standard curve, eg, the plurality of additional sample points. It may be inferred from one or more of the (first defined) sample points that are near the sample point from the sample point.

In this embodiment, determining one or more of the points closest to the sample point on the curve, the distance from the sample point to the closest point on the curve, and the side of the curve where the sample point should be treated as is. Can be possible. The information may be determined in standard space (thus requiring that the sample point be converted to standard space and / or the information determined in standard space be converted back to world space. It may be decided within the world space.

Further, in this embodiment, it may not be necessary to use one or more nearby sample points to determine the actual value of a particular variable, but to determine if the value of the variable is above or below the threshold. There may be a need. It may then be used to determine if the value of the variable needs to be determined independently or more accurately, eg, for a sample point that is near the input curve. For example, a sample in which the additional sample point is close to or near a nearby sample point, using one or more enclosing sample points for which the closest point and / or distance has already been determined for the additional sample point. It may be possible to determine if it is far from the point. If the additional sample points are far apart, it may be sufficient to simply store the distance to the curve (or the threshold or default value indicating that the points are far apart) with respect to the nearby sample points. If the additional sample points are closer, it may be necessary to determine the closest point on the curve to the sample points in standard space as relative to the initial set of sample points.

In this embodiment, preferably, information determined for an initial set of sample points, such as a point on the curve closest to the sample point, the sample so that these comparisons can be made for additional sample points. The distance from the point to the nearest point on the curve and one or more of the sides of the curve for which the sample point should be treated as is are stored, for example, in the cache.

When there are multiple input curves, the multiple sample points in the world space surrounding each input curve can be the same for each input curve. For example, the plurality of sample points can enclose all input curves (thus, as will be described later, may give the possibility of testing all input curves at the time of drawing), but preferably each input. The plurality of sample points surrounding the curve are selected separately for each input curve, eg, just surrounding the input curve, so they preferably form a subset of the sample points in world space. For example, a (single) bounding box can be drawn to surround all input curves, but preferably a separate bounding box is drawn to surround each input curve, with multiple sample points in it. Is defined.

With respect to the sample points in world space that are converted to standard space, the points on the standard curve in standard space that are closest to the converted sample points may be determined in any suitable and desired manner. Preferably, the points on the standard curve closest to each of the transformed sample points are analytically determined in standard space. The closest point may be determined by determining a point on the standard curve whose tangent to the standard curve is orthogonal to the vector from the transformed sample point to the point on the standard curve (several standard curves). In contrast, this may return multiple points on the curve that satisfy the condition, thus comparing the distances from the transformed sample points to the points on the curve to determine the closest point, eg, It may be necessary to discard points that fall outside the finite portion of the standard curve and / or select a point on the standard curve that has the shortest distance from the transformed sample point). Depending on the definition of the input curve, such an analytical calculation may be possible in world space, for example, when the input curve is defined as a Bezier curve, but for example, when the corresponding standard curve is a parabola. It may be possible within standard space.

When the input curve has a fixed length, eg, defined by a start and end points, some start or end points of the standard curve are the vector from the transformed sample point to the point on the standard curve and the standard curve. The tangents may be closer than the (closest) point on the orthogonal standard curve (eg, outside the part), eg, the start or end point of the curve is the point on the curve closest to the sample point. May be good. Thus, preferably, the step of determining the point on the standard curve closest to the transformed sample point also determines the distance from the transformed sample point to some of the start and end points of the standard curve. It comprises the step of determining if one of the start point or the end point is a point on the standard curve closest to the transformed sample point (thus preferably the processing circuit is so configured).

Preferably, the step of determining the point on the standard curve closest to a particular transformed sample point is the transformed sample point and the point on the standard curve in the standard space closest to the transformed sample point. Including the step of determining the distance between (and thus preferably the processing circuit is configured as such), eg, determining the point on the standard curve closest to the transformed sample point in standard space. The step may include a step that minimizes the distance between a given transformed sample point and the standard curve. Thereby, for each of the sample points surrounding the curve, the distance from the sample point to the corresponding nearest point on the curve with respect to the sample point is determined, and when the rendering output is generated, for example, a reference numeral. As part of the distance field, it is possible to use the distance to the closest point on the curve without having to recalculate the values in world space when generating the rendered output.

A look-up table may be used to determine the distance between the transformed sample point and the closest point on the standard curve. Alternatively, the distance between the transformed sample point and the closest point on the standard curve may be analytically calculated, for example, as a hardware-burned analytical calculation. If you use a lookup table, do this (for example, minimize the amount of data stored in the lookup table because most of the input curve corresponds to the portion of the standard curve near the top of the parabola. It may be provided over a specific (eg, finite) range of the standard curve. Analytical calculations are performed outside this range. In addition, multiple lookup tables may be used to cover different parts of the standard curve, for example, for use as needed, and the distances from multiple sample points are pre-determined and stored. The curve. This helps reduce the need to recalculate these distances and thus reduce real-time processing.

In a further embodiment, for example, a standard curve corresponding to the input curve (eg, in addition to the lookup table stored in the texture and provided to determine the distance from the sample point to the closest point on the curve). , Including the determined conversion from world space to standard space) may be predetermined and stored. Further information, such as the distance from the sample point to the nearest point on the curve (eg, by defining a bounding box around the input curve (s) around which the sample point can be defined) and / or the input curve or Formulas for use in determining the maximum range of curves may also be appropriately pre-determined and stored as needed.

For example, when the input curve (s) define the glyphs to be rendered, the font format may include some or all of that information.

When the input curve is straight, preferably the input curve in world space is on an axis, eg, the x-axis, in standard space, preferably using one or more of rotation, transformation and expansion as needed. Will be converted. The closest point on the standard curve is then simply, for example, the x-coordinate of the transformed sample point along the axis on which the straight line is transformed. When the input curve has a fixed length, for example, when defined by the start and end points, for example, the x-coordinate of the transformed sample point exists, for example, between the x-coordinates of the start and end points of the standard curve. If so, the point on the standard curve closest to the transformed sample point is the x-coordinate of the transformed sample point. For example, when the x-coordinate of the transformed sample point is outside the start and end points of the standard curve, the point on the standard curve closest to the transformed sample point is among the transformed sample points. It is close to the start point or end point. For an input curve with a fixed length, a straight line segment in standard space can be expanded to run between x = 0 and x = 1 in standard space, but this is not necessary.

If the point closest to the transformed sample point on the standard curve is determined in standard space, then the closest point is the inverse of the transformation between world space and the standard space determined for the input curve, for example. May be used to convert from standard space to world space. Thus, for each sample point, the method transforms the determined closest point from standard space to world space using the reverse of the transformation between world space and standard space, thereby producing an input curve. For each of the sample points in the world space surrounding, a step may be included (and the processing circuit may be configured as such) to determine the corresponding closest point on the input curve in the world space. The step of producing the rendered output may then use the closest determined point on the input curve to the sample point in world space when generating the rendered output. However, this may not be necessary, as described below. This is because, for example, the use of the closest determined point to determine the distance from the sample point to the curve and / or to which side of the curve the sample point is located is similarly used in standard space. This is because it may be carried out.

When there are multiple input curves, for example, the outline of the shape (eg, glyph) is formed, and the closest point on the corresponding standard curve for each sample point is set separately for each of the plurality of input curves. For example, it may be determined for another set of sample points surrounding each input curve, the determination being performed within a standard space determined for each input curve, of multiple standard curves and / or input curves. The closest point in each (which may be the start or end point of the standard or input curve) is determined for a set of sample points surrounding each input curve, and the closest point determined in standard space. Convert to world space if necessary (again, if desired, a set of sample points per input curve may enclose one or more or all of the input curves).

These closest points on a plurality of curves are then compared to each other (when the sample points determine the closest point in standard space for two or more, for example, all of the input curves). For example, by comparing the distance from the sample point with each of the closest points on the plurality of curves, the closest point on the plurality of curves to each sample point can be determined. This comparison between the closest points, for example using the distance from the sample point to the closest point, may be performed in world space or standard space. When performed within standard space, it may be necessary to use conversion of input curves to standard space, for example if different enlargements are needed to convert different input curves to standard space. When performed in world space, the closest determined point and / or the distance from the sample point to it, if necessary, from standard space using the inverse transformation determined for the input curve, respectively. It should be transformed into world space.

In another embodiment, for each of the sample points, the closest point to the overall curve (or a subset thereof) is selected appropriately (eg, the sample points surrounding all the input curves). It may be determined (for the sequence). This allows a single closest point on one of a plurality of curves (which may be the start or end point of one of the curves) to be determined for each of the sample points. The closest point is looped on one or more of the plurality of input curves to determine the closest point to each sample point, that is, the closest point to one or more of the plurality of curves. It may be determined by determining whether it exists.

Again, the determination of the closest point in the embodiment may be performed in world space or standard space, with any transformation and / or expansion performed as needed. Care must be taken to determine which of two or more curves has the closest point to a sample point that is near the end of the curve, especially when operating in standard space. For example, the two input curves may form corners of the shape so that it is not immediately clear which of the curves the sample point is closest to.

In both of the above embodiments, once the (single) closest point on a plurality of curves to a sample point is determined, the identification of the standard curve or input curve where the closest point exists is identified for each sample point. It is preferably determined (and stored, for example).

Appropriate, if necessary, for the distance from each of the sample points to the corresponding (single) nearest point on multiple curves as a whole, for example, either in standard space or in world space. Similar decisions may be made (in world space or standard space) by comparing the distances for each of the multiple input curves (using transformations).

One or more points on a plurality of curves closest to a given sample point may be determined using all of the plurality of input curves, but preferably, the closest point is the plurality of points. Is determined for only a portion of the input curves of, eg, a preselected group of one or more input curves is determined from the plurality of input curves. One or more input curves from the plurality of input curves, eg, a preselected group, in any suitable and desired manner, eg, either multiple inputs or corresponding standard curves (eg,). The choice may be based on a rough determination of whether each of the (transformed) sample points is closest and / or which of the input curves is in the tile containing the sample points in question. Selecting only a finite number of input curves to use for that decision helps reduce the processing required.

(It is understood that when the rendered output contains a glyph, the outline of the glyph is defined by one or more input curves and the area inside the input curve needs to be properly shaded to display the glyph. There can be multiple input curves that surround any particular point within the glyph or are close to any particular point outside the glyph, but whether the sample point is inside or outside the glyph. The determination may be made simply by determining which of the plurality of input curves has the closest point).

When the distance between the transformed sample point and the point on the standard curve closest to the transformed sample point is also determined in standard space, the distance is preferably for each of the sample points. , The inverse transformation from the standard curve to the input curve is used, for example, to transform from standard space to world space along the nearest point on the curve.

Render output the closest points (on the standard or input curve) in standard space or world space, and the distance from the sample point in standard space or world space to the closest point, respectively, when available. It may be passed directly to the processing circuit used to generate (the distance from the transformed sample point to the nearest point on the standard curve has not yet been determined in standard space and / or in world space. When not converted to, preferably, the distance from the sample point in world space to the closest point (on the input curve) is, for each sample point, eg, the closest point on the input curve and the sample point. It is determined using, which may be determined in standard space or world space, if desired). However, the method may include a step of storing the closest point on the curve for each sample point (and the processing circuit is configured as such). For each closest point, the value may be stored in standard space or world space as needed.

If information has already been determined for an initial set of sample points, eg, for a further set of sample points based on the distance from the sample points to the closest point on the curve, then that information is also eg, for example. , It is preferable to store according to the corresponding information determined for the initial set of sample points.

When the distance from the sample point to the nearest point is determined (in standard space or world space, if necessary), the method is preferably the closest on the curve from the sample point, for each sample point. It includes, for example, a step of storing the distance to a point along the closest point on the input curve for each sample point (and the processing circuit is configured as such). The stored value for each distance may be in standard space, but is preferably in world space. Redetermining the distance (eg, using the closest point on the curve stored for each sample point) by storing the converted distance from the sample point to the closest point on the curve. The need is avoided.

The value of the distance may be stored in any suitable and desired way (as needed, in standard space or world space). The distance value may be stored, for example, in the raw form in which it was calculated. However, in one embodiment, when the distance value is greater than the threshold, the distance value is truncated to, for example, set to the threshold or default value. The storage space can be minimized only by storing the determined distance value up to the threshold value. It is important that the sample points are close to a curve and have knowledge of the distance, for example, the actual distance value is available when it can be used to generate a special rendering effect. However, outside the range of the distance, for example, for a sample point far away from the input curve, it is at least a threshold, so it is necessary to know the exact value of the distance to the nearest point on the input curve. It does not have to be.

When there are multiple input curves, the distance from the sample point to the curve as a whole (for example, along the identification of the curve where the closest point exists) or the sample point for each of the plurality of input curves. The distance from to the curve, or in its place, the corresponding closest point (s) may be stored, if desired.

The distance (s) (or the closest point (s) instead) in any suitable and desired format (needed) so that the information is available when generating the rendered output. It may be stored in any suitable desired storage (in standard space and / or world space accordingly). In a preferred embodiment, the distance (s) (or the closest point (s) instead) are stored in the form of one or more graphics textures for each of the sample points. Not only is this intended for graphics textures to store data at points in an array of specific geographic locations, but it is also commonly incorporated into graphics processing systems by storing data in the form of textures. It is particularly advantageous and beneficial because the existing texture mapping process can be used to generate rendered output in the manner of the present invention.

Also, the generation of this form of graphics texture is considered to be novel and advantageous in itself. Therefore, the present invention also extends to the construction of such textures.

Therefore, according to a third aspect, the present invention provides a method of generating a graphics texture for use in a graphics processing system when generating a rendered output using an input curve. The method is
For the input curve defined in world space
Steps to determine the part of the standard curve defined in the standard space corresponding to the input curve and the transformations required to map the input curve to part of the standard curve,
For each of the multiple sample points in the world space surrounding the input curve
Convert the sample point from world space to standard space using the determined transformation between world space and standard space.
In standard space, determine the point on the determined part of the standard curve that is closest to the transformed sample point.
Thereby, for each of the transformed sample points in the standard space surrounding the standard curve, the step of determining the corresponding closest point on the standard curve in the standard space, and
For each of the sample points, the step of determining the distance from the sample point to the determined nearest point on the curve, and
A step in generating a graphics texture containing an array of texels, where each texel corresponds to at least one of the sample points and for the at least one sample point the curve from at least one sample point. The steps associated with the determined distance (s) to
including.

Seen from a fourth aspect, the present invention provides an apparatus for generating a graphics texture for use in a graphics processing system when generating a rendered output using an input curve. The device is
For the input curve defined in world space
Determine the part of the standard curve defined in the standard space corresponding to the input curve and the transformations required to map the input curve to part of the standard curve.
For each of the multiple sample points in the world space surrounding the input curve
Convert the sample point from world space to standard space using the determined transformation between world space and standard space.
In standard space, determine the point on the determined part of the standard curve that is closest to the transformed sample point.
Thereby, for each of the transformed sample points in the standard space surrounding the standard curve, the corresponding closest point on the standard curve in the standard space is determined.
For each of the sample points, determine the distance from the sample point to the determined nearest point on the curve.
It includes a processing circuit configured to generate a graphics texture containing an array of texels. Each texel corresponds to at least one of the sample points and is associated with the determined distance (s) from at least one sample point to the curve for the at least one sample point.

As will be appreciated by those skilled in the art, these aspects and embodiments of the invention may optionally include any one of the preferred and arbitrary functions of the invention described herein. It is preferable to include it.

For example, the distance from each sample point to the corresponding closest determined point on the curve may be determined in standard space or world space. The determined distance (s) may be stored in standard space or world space, and thus textures may be stored in standard space or world space (ie, texels in standard space or world space). May be placed). But preferably the texture (and texels), and thus also preferably, the determined distance is stored in the intermediate space. The intermediate space may be any suitable desired space. Preferably, the intermediate space is an expanded and / or transformed version of world space. This may be set, for example, to the texel reference point of the bounding box surrounding the sample point, eg, the origin in the lower left corner.

Similarly, each texel in the one or more textures preferably associates it with the above-mentioned information about the solution (s) on the standard curve for that texel position. In other words, each texel represents at least one position in standard space and stores information about the distance to the nearest point on the standard curve with respect to that position in standard space. For example, preferably, the information may include a parametric value of the closest point (s) and / or an identity of the input curve (s) in which the closest point (s) resides.

If the information is stored in the form of a texture, the texture (s) can be of any suitable desired size (ie, including any number of texels as needed), and each texel will have it. It may have any desired number of associated data components. However, each texel preferably associates it with information related to a single discrete position in standard space only.

The texture may also store any other suitable desired information. For example, the texture defines an input curve (s) in world space (including arbitrary control points of the input curve (s)) and a standard curve (s) in standard space (standard curve (s)). Includes any control point (possible), conversion of the input curve (s) to the corresponding standard curve (s), (eg, determined closest point, distance to the closest point and / or input) Stores anti-aliasing information (for determining which side of the curve the sample point is on) and one or more of the eccentricity of the input curve and / or standard curve when the curve is elliptical or bicurve. May be good. The texture may also store, for example, post-processing information about the input curve (s) that the input curve should be drawn as a stroke curve, preferably also its width (in this example, the distance to the curve). , Used to determine if the sample points are inside or outside the width of the stroke curve).

When there are a plurality of input curves, preferably, information about the plurality of different input curves is stored together, for example, in the same texture, as detailed above. This may be done, for example, by spatially separating the input curve within the texture and then sampling the appropriate region within the texture for the input curve in question. Further, when the input curve (s) are associated with glyphs, the texture preferably stores information about all glyphs that produce the font, eg, in the form of a font atlas. For the plurality of input curves, this may be done, for example, by spatially separating the glyphs within the texture and then sampling the appropriate area within the texture for the glyph in question.

As described above, in these embodiments and embodiments of the invention, the sampled texture points (texels) surrounding the input curve are, for example, from a texture point in a standard interval or world space to the closest point on the curve. The texture representing the input curve is configured to give a sampled texture value that indicates the distance of, and perhaps the point on the curve closest to the texture point in world space, and any other information that can be stored in the texture. The curve. Therefore, when sampling a texture, the sampled texture value may be used to determine on which side of the curve the sampled points are located, and then this is used. , Input curves can be used to generate rendered output.

As an addition or alternative to storing the required information in the texture, for example as an intermediate step, part or all of the determined information, or as part of the process of determining the information used to generate the rendered output. The determined information may be stored in any suitable desired location within the graphics processing system, eg, the cache described above. This may be useful when the information is determined in real time. In another embodiment, the determined information may be stored locally, eg, in on-chip memory in a graphics processing system, eg, pixel local storage.

Any other suitable desired information that can be determined using the closest point on the curve (eg, stored in the texture), eg, the closest point along the distance from the sample point to the closest point on the curve. Once the array of is determined (eg, stored in a texture), the rendered output with the input curve is then on the standard curve for the transformed sample points in standard space in any suitable and desired way. Can be generated using the closest determined points of. This can be applied directly to the determined closest point on the standard curve, or from information derived from it, to an input curve in world space, for example (in standard space or world space, if necessary). It may be performed from the distance from the nearest point or the sample point to the closest point on the curve when converting back.

As mentioned above, the step of determining and storing the closest point to the curve may be performed offline and stored, for example, in a texture for later use when generating rendered output. Preferably, the closest points on the curve are determined in real time, but preferably the closest points on the curve (and / or related information such as distance) are also those in the future. As available, for example, if the same input curve is used to later generate the rendered output, it will be stored, for example, in a texture.

Preferably, the rendered output is generated using the determined distance from the closest determined point on the curve (in standard space or world space as needed) to the sample point. Therefore, in a preferred embodiment, the distance from the determined closest point on the curve to the sample point is for each of the plurality of sample points surrounding the curve in order to generate a rendered output using the input curve. When determined, the method is
For each of the multiple sample points in world space
A step of sampling the determined distance from the determined closest point on the input curve to the sample point at a position in the world space corresponding to the sample point.
It includes a step of generating a rendered output using the determined distance to the sample point in world space (and the graphics processing system includes a processing circuit so configured).

The rendered output may generate the determined closest point using any suitable and desired method, eg, through the use of the determined distance described above. In a preferred embodiment, additional information (s) related to the input curve and sample points may be determined when generating the rendered output using the closest determined points. And / or the closest point may be determined so that it can be used, for example, in a texture to generate rendered output.

In a preferred embodiment, the method is
For each of the multiple sample points surrounding the curve
The closest determined point on the curve is used to determine on which side of the curve the sample point should be treated as is.
As a result, for each of the sample points surrounding the curve, it is determined on which side of the curve the sample points should be treated as they are.
A step that uses the determination on which side of the curve the sample point should be treated as is when generating the rendered output, and
(And the graphics processing system includes processing circuits so configured). The step of determining on which side of the curve the sample points should be treated as is may be performed in standard space or world space, as appropriate.

Therefore, once they are determined (eg, sampled from a texture), each of the sample points on either side of the curve is used using each of the determined closest points on the curve. It is preferable to determine whether or not should be treated as it is. The decision may be made in any suitable and desired manner. By knowing which side of the curve the sample point is on, the information can be used to generate a rendered output. For example, if the sample points are within an object (eg, with an outline that is at least partially defined by the input curve), the color of the object may be shaded, or at least (eg, by the input curve). If present in a shadow (projected by an object with a partially defined outline), it may be shaded appropriately.

For each sample point using the closest determined point on the curve, the step of determining on which side of the curve the sample point should be treated as is is the tangent check of the sample point for the curve. May include. When the distance between the sample point and the corresponding closest point on the curve is determined for the sample point, determine on which side of the input curve the sample point should be treated as is. The step may also use the distance from the sample point to the closest point on the curve. Preferably, the step of determining the distance from the sample point to the corresponding closest point on the curve also includes the step of determining on which side of the curve the sample point should be treated as is. Again, this may be done in standard space or world space.

When there are multiple input curves, and the closest point on the curve is determined (for example, stored) for each sample point for multiple input curves as a whole, this closest point is used for input. It may be determined on which side of the curve the sample point should be treated as is. Alternatively, when the closest points are determined for each of the plurality of curves (for example, at least a part thereof) for each sample point, these closest points are set on which side of the curve the sample points. May be used together to determine if should be treated as is.

Preferably, when there are multiple input curves, the step of using the determined closest point to determine on which side of the input curve the sample point should be treated as is is the multiple curves. Includes (and preferably, the processing circuit is configured as such) a step of performing an average tangent check of the sample points associated with (eg, at least a portion thereof). The average tangent check may be performed on the glyph using all of the determined closest points and the curves, for example, but the average using only a subset of the curves. It is preferable to perform a tangent check. The average tangent check may be performed in standard space or world space.

Preferably, the subset of the curves used for the mean tangent check is used, for example, to determine the closest point on the curve (which may be the closest point to the sample point). Preselected using the same subset created.

When the input curve contains a straight line, the step of deciding on which side of the curve the sample point should be treated as is, preferably using the closest transformed point, is that the sample point is in standard space. Includes a step to determine if it is above or below the inner axis (and preferably the processing circuit is configured as such).

When it is determined for each of the sample points the distance between the sample point on the curve and the corresponding closest point, and / or on which side of the curve the sample point should be treated as is. One or both of these pieces of information may be stored, for example, in a texture. The stored information may be in standard space and / or world space. Therefore, once both of these pieces of information have been determined, they may be used (eg, stored) in the form of a signed distance field (eg, on the side of the curve, the sampling is the stored curve). To determine the sign of the distance to). As mentioned above, preferably, the step of determining the distance also determines on which side of the curve the sample points are present, thus facilitating these two pieces of information for each sample point. May be used and / or stored together.

Preferably, the step of producing the rendered output should treat the sample point as is, on either side of the curve, and / or the distance from the sample point in standard space or world space to the closest point on the curve. Use the determination (and the processing circuit is configured that way). When the distance from the sample point to the closest point on the curve has been previously determined, the determined value, eg, the value stored in the texture, can be used. Alternatively, the distance from the sample point to the closest point on the curve may be determined from the sample point and the closest point on the curve.

Therefore, in a particularly preferred set of embodiments, both the distance from the sample point in standard space or world space to the closest point on the curve, and on either side of the curve, the sample point is treated as is. The render output is produced, for example, in the manner of a signed distance field, using the determination of what should be done.

Even if the rendered output is generated in world space to determine the closest points on the curve (from which they are converted to standard space), for example, in the space in which the sample points were originally defined. Well, therefore the distance to the nearest point may be generated, for example, in the space stored in the texture, or the rendered output may be generated, for example, in a different "surface" space corresponding to the space in which the display is output. You may. This latter case may be useful, for example, when drawing text in 3D on a surface that is not flat to the observer. This may be useful in virtual or augmented reality.

In this latter embodiment, the closest determined points on the curve may be sampled directly or used to produce rendered output. However, preferably, in order to generate a rendered output using the input curve, the distance from the determined nearest point on the curve to the sample point is for each of the plurality of sample points surrounding the curve. When determined, the method preferably
For each of the multiple sample points in surface space
A step of sampling the determined distance from the closest point on the input curve to the sample point at a position in world space corresponding to the sample point in the surface space.
It includes a step of generating a rendered output using the determined distance to the sample point in world space (and the graphics processing system includes a processing circuit so configured).

When it is determined (eg, stored) on which side of the curve the sample points should be treated as-is, the information is preferably also at each of the plurality of sample points in surface space. In contrast, it is sampled at a position in the world space that corresponds to the sample point in the surface space, and then with rendered output, eg, with the appropriate transformation of information between the world space and the surface space, if necessary. Used to generate. In another embodiment, the distance from the sample point to the closest point on the input curve and / or on which side of the curve the sample point should be treated as is is determined within the surface space. You may.

When generating rendered output in surface space, preferably the first step in generating rendered output using an input curve is multiple in surface space (the space in which the rendered output is generated, eg, displayed). For each of the sample points, it is to sample (and preferably) the determined distance from the closest point on the curve to the sample point at a position in world space corresponding to the sample point. Also determines on which side of the input curve the sample point should be treated as is). For this reason, an appropriate transformation between the surface space and the world space for the sample point may need to be performed, depending on the relationship between the surface space and the world space. Further conversion from world space to standard space also needs to be performed, for example, when the information determined for the sample point only needs to be determined in standard space and not converted back to world space. Might happen.

For example, when the input curve forms at least part of an object, eg, a glyph to be drawn, so that the rendered output can relate to a 2D image, the surface space exists in a plane parallel to world space. You may. In this case, the sample points in the surface space may be provided at the same density as the sample points in the world space (so that they may need to be properly mapped to the corresponding sample points in the world space). ) Just as multiple sample points in the surface space may directly correspond to multiple sample points in the world space, the surface space may be the same space as the world space (or within the magnifying factor). ..

In another embodiment, the sample point is when the rendered output is related to a 3D scene and, for example, a curve is used to create a shadow, or when a write is displayed on a curved surface (eg, for virtual reality). The transformation of may be performed between surface space and world space.

As mentioned, input curves (and textures, if provided) may be used to draw objects that differ from what the input curve forms at least in part, eg, with shadows. However, preferably, it forms at least a part of the object on which the input curve is drawn, eg, outlines it. For example, the object to be drawn may contain glyphs (as part of the font). The input curve may be defined in any curve representation, eg, in the form of vector graphics. Preferably, the input curve is defined in a scalable vector graphics (SVG) format.

Information about the input curve used when generating the rendered output, such as the closest point on the input curve, the distance from the sample point to the closest point on the input curve, and / or the sample point on either side of the input curve. Once it is determined that the should be treated as is, the rendered output may be generated in any suitable and desired manner, eg, directly in world space or from surface space. Once the texture is determined and stored, this may be done, for example, using any suitable graphics texture mapping process.

In a preferred embodiment, one or more primitives covering the scene area where the rendered output appears are first generated in surface space, for example, and then input on the scene area covered by the one or more primitives. Display the rendered output, for example, by using the determined information on the curve, eg, by applying a texture to the one or more primitives and thereby shading the one or more primitives accordingly. May be generated for.

The one or more primitives may be generated as needed by defining one or more bounding boxes or surrounding polygons that cover the scene area where the shape to be drawn appears, eg, glyphs. ..

When generating the primitive, it may be necessary to ensure that the generated primitive (s) sample only the desired (and appropriate) region of the texture (which is the multiple input curves). (Or, for example, glyphs) may be represented by the same texture).

The generated primitive, then multiple generated primitives and fragments, eg, a plurality of textures inside a texture that represent the input curve applied to each sample point (and / or fragment) of the one or more primitives. The sample point may be rasterized by sampling the position in the texture corresponding to the position of the sample point (and / or fragment) of the primitive (preferably a suitable texture such as bilinear filtering). Textures should be sampled using a filtering process). This produces an array of sample points that cover one or more primitives in surface space, and transforms these sample points into world space where the determined information can be sampled, for example, from textures. There may be.

On which side of the input curve the sampled information, eg, texture value, should be treated as is and / or the distance of the sampled position (s) to the input curve. Is used to properly shade the corresponding sampling position (s) using the determination of. Based on this decision, multiple sample points will have red, green and blue (RGB) color values and "alpha" transparency values to allow, for example, to accurately display scenes containing glyphs, if desired. Is the assigned data such as.

As will be understood, when the distance from the sample point on the input curve to the nearest point is available to be used when generating the rendered output, it can be used, for example, for the edges of the input curve. It may be possible to perform more complex rendering effects, such as rotation, shading, etc., than when only thresholds are available.

The present invention is applicable to renderers of any form or configuration, such as renderers with a "pipeline" arrangement, in this case the renderer is in the form of a rendering pipeline. In a preferred embodiment, it applies to the hardware graphics rendering pipeline. Various functions and elements of the present invention can be implemented, if necessary, for example, preferably with appropriate functional units, processing logic, processors, microprocessor arrangements, and the like. Further, in one embodiment, it is considered that the present invention may be implemented in the graphics processing pipeline with the minimum functions, for example, the minimum required version. Such a system may be suitable for use in low power devices such as wearables, e-readers and the like.

The present invention is applicable to all forms of rendering such as immediate mode rendering, delayed mode rendering, tile based rendering and the like. In one preferred embodiment, the invention is used in and for delayed mode rendering and tile-based renderers.

As can be seen from the above, the present invention is not particularly comprehensive, but is applicable to 2D or 3D graphics processors and processors, and thus aspects of the invention described herein. Extends to 2D or 3D graphics processors and 2D or 3D graphics processing platforms that include or operate according to any one or more devices. Subject to any hardware required to perform the particular functions described above, such a 2D or 3D graphics processor may be any one or any of the usual functional units included in the 2D or 3D graphics processor. Can include multiple or all. In a preferred embodiment, the system is particularly designed to determine, for example, the point on the curve closest to the sample point (eg, in standard space) and / or the distance from the sample point to the closest point on the curve. Includes configured fixed-function hardware units.

The present invention is applicable to any suitable form or configuration of graphics processor. The present invention is particularly applicable to tile-based graphics processors and graphics processing systems. Therefore, in a preferred embodiment, the graphics processing system and the graphics processing pipeline are tile-based systems and pipelines, respectively.

In a particularly preferred embodiment, the various functions of the invention are performed on a single graphics processing platform that generates and outputs drawn, eg, fragments, eg, data written to a display frame buffer. To.

The present invention can be implemented in any suitable system, such as a well-configured microprocessor-based system. In a preferred embodiment, the invention is implemented in a computer and / or microprocessor based system.

Various functions of the present invention can be performed in any desired and appropriate manner. For example, the functions of the present invention can be implemented in hardware or software as needed. Thus, for example, unless otherwise specified, such as appropriate dedicated hardware elements and / or programmable hardware elements in which the various functional elements, steps and "means" of the invention can be programmed to operate in a desired manner. It may include suitable one or more processors capable of performing various functions and the like, one or more controllers, functional units, circuits, processing logic, microprocessor arrangement and the like.

It should also be noted that various functions, stages, etc. of the invention may be duplicated and / or run in parallel with a given processor, as will be appreciated by those skilled in the art. Equally, the various processing steps may share processing circuits and the like, if desired.

Subject to any hardware required to perform the particular functions described above, the data processing system and pipeline may include any one or more or all of the normal functional units included in the data processing pipeline. Can include.

It is also preferred to those skilled in the art that all of the described embodiments and embodiments of the present invention may, optionally, include any one or more or all of any of the above-mentioned suitable functions. Understood.

The method according to the invention may be implemented using software, eg, a computer program, at least in part. Therefore, from a further aspect, the present invention is a computer software specifically adapted to perform the methods described herein when installed in a data processing means, such program elements performing in the data processing means. All of the computer program elements, including the computer software code portion for performing the methods described herein, and the methods described herein when the program is run on a data processing system. It can be seen that it provides a computer program that includes code means adapted to perform the steps in. The data processor may be a microprocessor system, a programmable FPGA (field programmable gate array), or the like.

The present invention also, when used to operate a graphics processor, provides a renderer or microprocessor system with data processing means to the processor, renderer or system in connection with the data processing means. Extends to computer software carriers that include such software to perform the steps of the method of the invention. Such computer software carriers can be physical storage media such as ROM chips, CDROMRAM, flash memory or disks, and signals such as wired electronic signals, optical signals or wireless signals such as to satellites. Can be.

It is not necessary to perform all the steps of the method of the invention by computer software, and thus from a broader aspect the invention is computer software for performing at least one of the steps of the method described herein. It is further understood to provide such software installed in a computer software carrier.

The present invention may therefore be appropriately embodied as a computer program product for use with a computer system. Such implementation may include a set of computer readable instructions fixed to a computer readable medium, eg, a tangible, non-temporary medium such as a disk, CD-ROM, ROM, flash memory or hard disk. The implementation can also include a set of computer-readable instructions that can be transmitted to the computer system via a modem or other interface device, on tangible media or intangibly using wireless technology. Tangible media include, but are not limited to, optical or analog communication lines. Radio technologies include, but are not limited to, microwave, infrared or other transmission technologies. The series of computer-readable instructions embodies all or part of the functionality described herein.

It will be appreciated by those skilled in the art that such computer-readable instructions can be written in several programming languages for use with many computer architectures or operating systems. In addition, such instructions may be stored using any current or future memory technology, or may be transmitted using any current or future communication technology. The memory technology includes, but is not limited to, semiconductor, magnetic, or light, and the communication technology includes, but is not limited to, light, infrared, or microwave. Computer program products are preloaded by a computer system, eg, on a system ROM or fixed disk, or distributed from a network, eg, a server or electronic bulletin board on the Internet or the Worldwide Web. It is considered that it can be distributed as an attached printed or electronic document, eg, a removable medium with shrink-packaged software.

Next, some preferred embodiments of the present invention will be described only by way of reference with reference to the accompanying drawings.

It is a figure which shows the outline of the workflow for drawing the text character string according to 1 Embodiment of this invention. It is a figure which shows the glyph for drawing which has an edge in which a series of input curves is defined as a part of the process in one Embodiment of this invention. It is a figure which shows the conversion of the input curve from the world space to the standard space as a part of the process in one Embodiment of this invention. It is a figure which shows the step of converting an input curve from the world space to the standard space as a part of the process in one Embodiment of this invention. It is a figure which shows the step of converting an input curve from the world space to the standard space as a part of the process in one Embodiment of this invention. It is a figure which shows the step of converting an input curve from the world space to the standard space as a part of the process in one Embodiment of this invention. It is a figure which shows the step which determines the point closest to the sample point on a standard curve as a part of the process in one Embodiment of this invention. It is a figure which shows the graphical representation of the signed distance field for three generated glyphs in one Embodiment of this invention. FIG. 6 shows a graphical representation of a signed distance field for each of the glyphs in a font graphically represented as a texture atlas for use with one embodiment of the present invention. It is a flow chart for carrying out the step of the process for drawing a glyph according to one Embodiment of this invention.

As mentioned above, the basic premise of the present invention is to render and output using the input curve, and the closest points on the input curve are various specimens determined for use in drawing. Determined for each of the points, for example, on which side of the input curve the sample points should be treated as-is. The input curve may form at least a portion of the object to be drawn (eg, at least a portion of its edges), or is used in some other way, for example, as part of the rendered output for shading. May form at least a portion of the shape or curve.

A preferred embodiment of the present invention will then be described in the context of drawing text in the form of glyphs (graphical representation of characters as part of a font) using a graphics processing system. The edge of the glyph is defined by one or more input curves. In that embodiment, a signed distance field is used to generate a texture representing the glyph, and then, for example, to determine on which side of the curve forming the edge of the glyph the sample points are located. A signed distance field is used to sample the texture to draw the glyph.

FIG. 1 shows an outline of a workflow for drawing a text character string according to one embodiment of the present invention. The first step (step 1) defines a set of rectangular bounding boxes, one for each glyph (characters in a word), when generating a rendered output containing a text string, eg, the word "reinforced". That is, the box is divided into two triangles to define the texture for each glyph. The bounding box may be provided by a font file, i.e. the box is entered into the graphics processing system and the spacing between each box determines the spacing between each letter in the word. A signed distance field for each independent glyph can then be calculated as described below (step 2, FIG. 1).

FIG. 2 shows a glyph 1 with an edge defined by a series of input curves.

In order to draw the glyph 1 for display, the glyph 1, or generally the information defining the glyph 1, is first input to the graphics processing system.

As shown in FIG. 2, the glyph 1 (for example, in the form of a vector graphics object) of the letter "O" is in the 2D world depending on the positions of the start and end control points and the intermediate control points of the curve. It is defined as a sequence of quadratic Bezier curves 2, 3, 4, 5, 6, 7, 8 and 9 in space. The exterior of the glyph is defined by four quadratic Bezier curves 2, 3, 4, 5 and the interior of the glyph is further defined by four quadratic Bezier curves 6, 7, 8 and 9. As will be described in more detail below, when the glyph 1 is drawn, the area between the internal and outer curves 2, 3, 4, 5, 6, 7, 8 and 9 will display the glyph 1. Is properly shaded.

During the rendering process, each of the constituent quadratic Bezier curves 2, 3, 4, 5, 6, 7, 8 and 9 that make up glyph 1 is first processed separately. For each of the quadratic Bezier curves 2, 3, 4, 5, 6, 7, 8, and 9, the point (in standard space) on the curve that is closest to each of the multiple sample points surrounding the curve. A curve in world space is mapped to the corresponding part of the standard curve in standard space so that it can be determined. (By determining the closest point in standard space, it is possible to perform an accurate calculation that can thus determine the accurately calculated signed distance field for the curve.)

The process of converting the first defined input curve in world space to the standard curve in standard space is described below.

Figure 3 shows a corresponding exemplary transformation T _UC into portions 10 '' of the standard curve 12 of a standard space 13 with respect to the input Bezier curve 10 in world space 11. The input Bezier curve 10 in world space 11 has a start control point b ₀ , an end control point b ₂ and an intermediate control point b¬ ₁ that define the curve in world space. The curve is mapped to a portion 10'' of the standard curve 12 in standard space 13 having a corresponding start point b _{0'and a} corresponding end point b _2'.

The predefined standard curve 12 as described above can transform all curves in a family of curves onto it (or at least part of it) using only rotation, transformation and / or uniform expansion. It is a single or fundamental curve and is defined within standard space 13. For example, in this embodiment where the input Bezier curve 10 defined in world space 11 is a quadratic curve (defined by three control points), the standard curve 12 is the curve y = x ² .

As will be appreciated, in order to implement this embodiment, the world standard transformation ( _TUC ), i.e., the input Bezier curve 10 defined in world space 11, is the corresponding portion of standard curve 12 in standard space 13. You need to determine which transformations you want to map to 10''.

FIG. 4 shows a method in which a transformation from an input Bezier curve 10 in world space 11 to a standard curve 12 in standard space 13 is derived for any given quadratic Bezier curve in this embodiment.

In the projection representation of the 2D space, the point in 2D space a, expressed as a vector A in 3D with components _{(a x, a y, 1} ). The expression is uniform and therefore A and λA represent the same point.

A typical quadratic curve is

It is defined by an expression of the form.

This is a component formula

Is equivalent to.

A typical quadratic Bezier curve is

It is defined from the equation by the coefficient that satisfies.

Assume that the inputs to the quadratic Bezier curve are three control points in 2D, namely b ₀ , b ₁ and b ₂ , b ₀ and b ₂ are two end points, and b ₁ is an intermediate point. .. From now on, it is necessary to determine the world standard transformation y = x ^{2 into the segment of the standard curve.}

As described above, the global standard conversion is defined by (defined by the matrix M _r) rotation, (defined by the matrix M _t) conversion and / or uniform expansion (matrix M _{s =} kI, k is It is a constant and dI is an identity matrix).

The first step is to set the coefficients of the component equation (a, b, c, f, g, h) to three control points b ₀ , b ₁ , b ₂ . Is to discover from. These coefficients can then be used to calculate the rotation, transformation and expansion required to bring the input Bezier curve onto the standard curve.

And the above coefficient is

Given in. _{Next, we need to find a world standard transformation (TUC} ), a 3x3 matrix, that transforms points in world space into standard space through combined rotation, transformation, and expansion. The effect of this transformation is to map the end point of the Bezier curve to the standard curve y = x ^2.

The first step in the process for determining the world standard transformation ( _{TUC ) in this embodiment is to determine the rotation component (rotation matrix Mr} ) of the transformation. The required rotation is determined as it is necessary to rotate the axis of symmetry 21 of the input quadratic Bezier curve 10 in world space 11 so that it is parallel to the axis of symmetry 23 of the standard curve 12 in standard space 13. See FIG. 4 (i).

The rotation is determined by calculating the rotation matrix M _r by operating the quadratic form of the input Bezier curve 10. First, the rotation matrix _Mr

Defined as. here,

And the signum function is

Is defined as.

Is guaranteed for a set of points on the input quadratic Bezier curve 10, so that the square root arguments in the equation for cosθ and sinθ will both be positive. (If a = b = 0, this is a straight line and should be identified in advance and treated separately as described below). Rotate the converted values for f and g accordingly

Can be determined through.

Once the rotation component of the world standard transformation is determined, the transformation component (ie, the rotation matrix M _t ) is determined next. The process is shown in FIG. 4 (ii).

The required transformation is determined as the nadir 20 of the rotated input curve 14 needs to be transformed to the origin (0,0) in the standard space 13, i.e. at the corresponding nadir 22 of the standard curve 12. .. The transformation is determined again by manipulating the quadratic form of the input Bezier curve 10 to calculate the _{transformation matrix M t.} First, the rotation matrix M _t

Is defined as. here,

Is. Finally, the uniform expansion component of the world standard transformation (ie, the augmented matrix _Ms ) is determined. This is shown in FIG. 4 (iii).

As will be understood, the input curve 10 in the world space 11 is once properly rotated and transformed into the standard space 13, i.e., the curve 16 in FIG. 4 (iii), y = x ² / | λ | It is in the form of. 1 / | λ | is an expansion factor to be determined. Again, the conversion is determined by operating the quadratic form of the input Bezier curve 10 in order to calculate the augmented matrix M _s. The first augmented matrix _Ms is

Defined by. here,

Is. A world standard transformation that requires the input Bezier curve 10 defined in world space 11 to be mapped to the corresponding part 10'' of the standard curve 12 in standard space 13, ie _TUC = M _s M _t M _r = Once 1 / | λ | M _t M _r is calculated, the actual part 10'' of the standard curve 12 can be determined by applying the determined transformation to the parameters of the input Bezier curve 10. The process is shown in FIG.

As shown in FIG. 3, an input Bezier curve 10 _{defined within world space 11 and having control points b 0} , b ₁ , b ₂ is the corresponding portion 10'of the standard curve 12 using the _{world standard transformation TUC.} Mapped to'.

Standard curve segment 10 '' of the start and end points b ₀ ', b _2' defines the parametric (x) range of the input Bezier curve 10 of a standard space 13. Thus, as shown in FIG. 3, the standard curve segment 10 ″ has a parametric range extending between _{the parametric positions x A} and x _{B in standard space 13.}

In this embodiment, the input Bezier curves 2, 3, 4, 5, 6, 7, 8, 9 in which a set of sample points in world space 11 form glyph 1 (eg, as shown in FIG. 2). Defined for each of. The closest point on the input Bezier curve to any given input Bezier curve (eg, the input Bezier curve 10 defined in world space 11 as shown in FIG. 3) is the input Bezier curve. Determined for each of the enclosing sample points.

The closest point on the input Bezier curve 10 to a given sample point in world space 11 is that the input Bezier curve 10 in world space 11 first becomes part 10'' of the standard curve 12 in standard space 13. It is determined by transforming the sample points in world space to the corresponding positions in standard space 13 using the previously determined world standard transformation _{TUC for mapping.} The point on part 10'' of the standard curve 12 that is closest to the transformed sample point in standard space 13 that corresponds to the sample point in world space 11 is the distance from the transformed sample point to the standard curve. Determined by minimizing.

For a transformed sample point using coordinates (u, v), the distance from that point to the curve can be written only in x-coordinates in standard space. That is,

Is. Minimizing D ² is easier, which is

give. here,

Is. This cubic equation is already in the canonical form, so a closed-form solution can be written down immediately. There are three cases to consider depending on the relationship between a and b.

When is, only one real root

Defined by. The cube root here is well defined because the arguments are guaranteed to be real and the cube root is defined for both positive and negative arguments (negative number cube roots are negative). There is.

When is, it is a case of degeneracy in which two of the three roots match. However, storage since global minimum is sought, which inflection points without any interest, above equation still holds the relative x _1, one minimum point is present (the one solution and the two solutions The transition curve between the needs to do is

Is. This curve is out of the focus of the parabola).

When, this corresponds to a cubic equation with three different real roots,

Given by. here,

Is. The middle root (depending on φ) is the global maximum and can be ignored. The outer two roots correspond to the minimum values and are of interest. It does not have to be that the absolute minimum (one of the two minimums) is the point on part 10 ″ of the standard curve 12 that is closest to the converted sample point. Because it can go outside the part 10 ″ of the standard curve 12. A check is performed to see if one or both of the outer roots fall inside part 10'' of the standard curve 12, and the standard curve corresponding to the two outer roots from the transformed sample point. The distances to points on part 10'' of 12 are compared, if necessary, so that the point on part 10'' of the standard curve 12 closest to the transformed sample point can be determined.

When the point on the part 10'' of the standard curve 12 closest to the converted sample point is determined, the distance from the position of the converted sample point in the standard space 13 to the point is calculated. (If this has not already been calculated as part of the determination of the closest point as described above).

The distance from the transformed sample point to the closest point on the curve may be determined by any suitable and desired method. Since the x-coordinate and y-coordinate of the converted sample point are known and the x-value of the closest point is determined, y = x ² (standard curve) gives the y-coordinate of the closest point. The distance is then easily determined from these two sets of coordinates.

One way to calculate the distance converts the 'start point b _0' of portion 10 'of the standard curve 12 to the origin, and then by rotating the end point b _2' to be placed in the positive x-axis is there.

Coordinates _(x 0, _{y 0)} with respect to the start point _{b 0} 'and the coordinate endpoints _{b 2} having _(x 1, _{y 1)'} having a portion 10 of the standard curve 12 with '', the first transformation matrix

Defined and rotation matrix

Is defined, where

Is. This rotates the end point to (d, 0). This point can be expanded to a point (1, 0), but there is no real benefit to doing so.

Therefore, the transformation matrix _{can be defined as R = R θ} T, and the coordinates of the transformed points are expressed as (u, v). Then the distance s to the nearest point on the curve is

Given by. Note that the sign of v also determines on which side of the line the sample point is, so it can be used as the sign of the signed distance field.

The distance is then compared to the distance from the sample point to each end of a portion of the standard curve. Of these three points, the point on the part 10'' of the standard curve 12 that has the smallest distance to the converted sample point is determined to be the point on the standard curve 12 closest to the converted sample point. To do.

Figure 5 shows a p ₀ point on the portion 10 '' of the standard curve 12 which is determined as the closest to the transformed sample point P in the standard space within 13. _{The closest point p 0} on the standard curve with respect to the transformed sample point P is determined to minimize the distance from the transformed sample point P to the standard curve 12. That it is, therefore, determines that the point p ₀ on the standard curve 12 is the point closest to the converted sample point P. This means that for this sample point and part of the standard curve, _{the distance d between the transformed sample point p and the nearest point p 0} is the end point of part of the standard curve from the converted sample point p. Because it is shorter than both distances to.

Also, as shown in FIG. 5, the distance from the converted sample point P to the nearest point p ₀ on the part 10 ″ of the standard curve 12 is minimized, and the distance for finding the closest point p _{0 is minimized.} If it has not already been determined by the process, it can simply be determined from these points.

When the input curve is a straight line, the curve defined in world space is transformed on the x-axis in standard space using a world standard transformation, including rotation and transformation (the input curve is also fixed length). It may sometimes be magnified to be placed between 0s and 1s on the x-axis of standard space, but this is not necessary). The closest point on the standard curve is then simply the x-coordinate of the transformed sample point in standard space. If the input curve has a fixed length with a start and end points and the x-coordinate of the transformed sample point is placed between the x-coordinates of the start and end points of the standard curve, then the converted sample point The point on the standard curve closest to is the x-coordinate of the transformed sample point. When the x-coordinate of the converted sample point exists outside the start point and end point of the standard curve, the point on the standard curve closest to the converted sample point is the start point or the end point of the conversion. It is closer to the converted sample point.

Once determined, (from transformed sample point P in the standard space 13 to the closest point p ₀ on the standard curve 12) the distance d, and if necessary of the standard curve 12 parts 10 '' on the most The near point p ₀ is then converted to world space 11 using the inverse _{of the conversion TUC} from world space 11 to standard space 13. That is, the distance between the points on the input Bezier curve 10 closest to the sample points in the world space 11 and these points is given. The process of determining the closest points on the input Bezier curve 10 with respect to the sample points and the distance between these points is repeated for each of the sample points in the array surrounding the input Bezier curve 10 in world space 11.

The distance to the input Bezier curve 10 for a further set of sample points may also be determined using the already determined distances to nearby sample points without the need for conversion to standard space and determination in standard space.

When this is completed for each of the sample points, the input Bezier curve 10 is completed so that the closest point on the input Bezier curve 10 and the distance to it are determined for each of the sample points in world space 11. Within the surrounding sequence, the process is repeated every 2, 3, 4, 5, 6, 7, 8 and 9 input Bezier curves forming glyph 1.

Within the array of sample points surrounding the entire glyph 1, using these multiple arrays of sample points corresponding to the multiple input Bezier curves 2, 3, 4, 5, 6, 7, 8, 9 forming glyph 1. For each sample point of, the closest points on multiple input Bezier curves 2, 3, 4, 5, 6, 7, 8, 9 as a whole, and also the distance between the closest points and the sample points of each. Can be decided. For a given sample point, the closest points on multiple input Bezier curves 2, 3, 4, 5, 6, 7, 8, 9 and the distances to them are simply determined independent input Beziers. It is determined by comparing the distances with respect to the corresponding sample points in each of the sequences of sample points surrounding curves 2, 3, 4, 5, 6, 7, 8 and 9 and selecting the minimum distance.

(Multiple input Bezier curves 2, 3, 4, 5, 6, 7, 8, 9 that are closest to a given sample point, and multiple input Bezier curves 2, 3, 4, that form glyph 1. By using only some of all of 5, 6, 7, 8, 9, for example, input Bezier curves 2, 3, 4, 5, 6, 7, 8, 9 that are clearly far from each other. It may be determined by discarding one or more of them. For example, for the glyph 1 shown in FIG. 2, the input curve on the left side of the glyph 1 with respect to the sample point existing on the right side of the glyph 1. 3 and 9 can be discarded).

If the side of the input Bezier curve 10 where each sample point in world space 11 resides has not yet been determined, for example, as part of determining the distance from that sample point to the closest point on the curve. Is determined by performing an average tangent check of the sample points in standard space 11 on standard curves corresponding to multiple input Bezier curves 2, 3, 4, 5, 6, 7, 8 and 9. .. Again, the plurality of input Bezier curves 2, 3, 4, 5, 6, 7, 8 and 9 for performing the mean tangent check on the sample points are the plurality of input Bezier curves 2, 3 forming glyph 1. It may be a part of all of 4, 5, 6, 7, 8, 9, and these may be a plurality of input Bezier curves 2, 3, 4, 5, 6, 7, which are closest to the sample point. It may correspond to the subset used to determine the points on 8 and 9.

The side of the input Bezier curve 10 where each sample point in world space 11 resides is at that distance, along with the distance between the sample point and the closest determined point on the input Bezier curve 10 with respect to the sample point. Used to give a sign. That is, a negative sign is given to the distance corresponding to the sample point existing inside the glyph, and a positive sign is given to the distance corresponding to the sample point existing outside the glyph.

The signed distance includes the determined closest point and the determined closest point on the input Bezier curve 10 to the sample point (plurality of input Bezier curves 2, 3, forming glyph 1). Along with the identification of the input Bezier curves (4, 5, 6, 7, 8, 9), each sample point surrounding glyph 1 is stored in the texture. That is, each texel in the texture in which the information is stored corresponds to the sample point. Therefore, as will be described later, the texture can store the glyph 1 as a signed distance field and then use it to draw the glyph 1.

The information stored in the texture for each texel (signed distance, identification of the determined closest point on the input Bezier curve, and the identification of the input Bezier curve where the determined closest point exists) is in a particular font. Determined as described above for each of the glyphs, the information for each of the glyphs (ie, including the signed distance field) is stored in the texture.

An exemplary signed distance field graphical representation is shown in FIG. 6 with respect to the glyphs representing the letters "c" 26, "2" 27, and "," 28. Points inside glyphs 26, 27, 28 are shown in black, along with a positive distance value (greater than a certain threshold) to each closest point on the input Bezier curve that defines the edges of glyphs 26, 27, 28. ing. The points outside the glyphs 26, 27, 28 are shown in white, along with a negative distance value (less than a certain threshold) to their closest point on the curve defining the edges of the glyphs 26, 27, 28. ing. Points close to the input Bezier curve (between positive and negative thresholds) that define the edges of glyphs 26, 27, 28 are shaded in gray, depending on their distance from the closest point on the curve. It is shown as.

Thresholds for signed distance values are only the appropriate (negative or positive) threshold (or some other default) when the value is stored in the texture and the value is higher or lower than a particular value. Value) is stored. The exact distance is not an issue, as this does not take into account when it takes into account when it is farther than a certain distance from the curve defining the edges of glyphs 26, 27, 28, when it produces rendered output. Because there isn't. The region of interest and where the exact distance from the sample point to the closest point on the input curve defining the edges of the glyphs 26, 27, 28 may be used to generate, for example, a particular rendering effect. For points near the edges of glyphs 26, 27, 28. Therefore, for these distance values between positive and negative thresholds, the values calculated for the signed distance field are stored without applying the thresholds.

The information stored in the texture may be calculated for each of the glyphs (characters) that form the font, such as characters, numbers and punctuation marks. FIG. 7 shows a graphical representation of the signed distance field for each of the glyphs in the font graphically represented as a texture atlas 29. The texture for each of the glyphs is spatially separated within the texture atlas 29 so that the appropriate area of the texture atlas 29 is sampled when a particular glyph needs to be drawn. In this example, the texture atlas 29 is tightly packed to save memory for the texture, so each glyph has a different size.

When a signed distance field is generated and stored in the texture to draw the glyphs (or to generate the complete texture atlas as shown in Figure 7), the required glyphs are in the bounding box of each glyph. The texture is sampled with an array of sample points, or the determined distance field is calculated with an array of sample points when the signed distance field is calculated in real time as part of the rendering process. By using it, it can be drawn. The step may use antialiasing techniques with the signed distance field, as shown in step 3 of FIG. The signed distance field may then be stored as part of the texture in the drawing operation on the texture.

The final drawn text string can then be displayed as shown in the "Results" step of FIG.

For example, if the writing should be displayed on a curved surface in three dimensions, the glyph should be drawn in a "surface" space (ie, the space where the rendered output is generated) that is different from the world space where the texture for that glyph is defined. You may. In this embodiment, one or more primitives are generated over a scene (display) area in the surface space in which the glyph is drawn so that the glyph is covered by one or more primitives.

These primitives are then rasterized in the usual way to the fragments passed to the shading pipeline for shading (which can happen, but that primitive is actually any sample point in the scene. If rasterization of the primitive does not produce a fragment (because it does not cover it to be visible), this means that the shape is not actually seen in the scene as it is visible, so the process Can be stopped here).
..

The appropriate texture is then applied to the primitive to draw the glyph. It represents the glyph for the location of one or more sample points in the scene covered by the primitive (s), using a texture map (or part of that texture map) that corresponds to the glyph to be drawn. This is done by applying the texture to one or more primitives by taking a texture sample from the texture (appropriate conversion to the world space where the texture is stored is performed on the sample points in surface space. Will be).

Each sampled texture value, including the signed distance to the closest point on multiple input curves that define the glyph, is then used to position the sample position inside the glyph, depending on the value of the signed distance. Determine if it should be drawn (drawn) as entering (ie, in fact, the inside of the edge of the glyph is defined by the input curve) or discard as entering outside the glyph.

FIG. 8 shows a flow diagram 30 for carrying out the steps of the above-mentioned process for drawing a glyph according to one embodiment of the present invention in the graphics processing pipeline of a graphics arithmetic unit (GPU).

First, the predefined path 31 is, for example, extracted from a font file generated by a central processing unit (CPU) and stored in the CPU. These paths use glyphs with straight lines (eg, defining the edges of the glyph), Bezier curves, arcs, and colors and other position data that define, for example, the start and end points of the input Bezier curve in world space. To define.

Then, using a lookup table (LUT) 33 that returns the distance between the transformed sample point and the closest point on the standard curve in standard space, the path (input curve) is (in the input curve). Processed by the processing steps of the graphics processing pipeline (SDF generator) 32 (in the manner described above with conversion to standard space for each) to generate a signed distance field for each glyph.

The route cache 34 then stores a signed distance field for the glyph, along with information about the route (input curve). The information is then compared to position data 35 within the fixed functional unit 36 (using the texture pipeline 37 to access values in the signed distance field) to generate the final texture to be drawn. This may include one or more of blending, masking and scissor test operations.

The final texture to be drawn is then passed to the frame buffer 38 for output, eg display.

From the above, rendering with one or more input curves by using standard space to determine the point closest to the sample point on the standard curve, for example, as part of generating a signed distance field. It can be seen that an efficient and convenient mechanism for producing output is provided. The mechanism can, for example, draw a mathematical representation of the input curve defined using vector graphics. This is a simple and accurate way to determine the information that provides a fast and accurate process for producing rendered output using input curves.

Providing a simple process for generating rendered output using such input curves helps reduce the processing and power load for the equipment running the process and is therefore battery operated and multifunctional. It can be used in simpler devices that do not require implementation of processing, such as mobile and wearable devices. In addition, the increased efficiency of the process allows more sophisticated rendering capabilities to be performed, or as needed, without the associated increase in equipment processing and power loads compared to previous techniques. The necessary information can be (re) calculated in real time.

31 paths (line, Bezier, arc, color, position)
32SDF generator 33LUT (parabolic X value)
34 route cache (glyph, segment (line, Bezier))
35 Position data 36 Fixed functions (blend, mask, scissor)
37 texture pipe 38 frame buffer

Claims (15)

A method of generating rendered output using input curves in a graphics processing system.
Determines the part of the standard curve defined in the standard space corresponding to the input curve and the transformations required to map the input curve to the part of the standard curve for the input curve defined in world space. Steps to do and
For each of the plurality of sample points in the world space surrounding the input curve,
The sample point is transformed from the world space to the standard space using the determined transformation between the world space and the standard space.
The distance from the transformed sample point to the start and end points of the part of the standard curve is determined, and one of the start point or the end point is on the standard curve closest to the transformed sample point. By determining whether it is a point, a point on the determined portion of the standard curve closest to the transformed sample point in the standard space is determined.
Thereby, with respect to each of the transformed sample points in the standard space surrounding the standard curve, a step of determining the corresponding closest point on the standard curve in the standard space.
When generating the rendered output, the step of using the determined nearest point on the standard curve with respect to the transformed sample point in the standard space, and
Including methods. The method of claim 1, wherein the step of determining the closest point on the standard curve includes a step of minimizing the distance from the transformed sample point to the standard curve. The step of determining the closest point on the standard curve is the step of determining the distance between the transformed sample point and the point on the standard curve in the standard space closest to the transformed sample point. The method according to claim 1 or 2 , wherein the method comprises. The method of claim 3 , further comprising storing the determined distance from the sample point to the nearest point on the standard curve for each sample point. For each of the plurality of sample points surrounding the curve
Using the determined closest point on the curve, it is determined on which side of the curve the sample point should be treated as is.
Thereby, for each of the sample points surrounding the curve, a step of determining on which side of the curve the sample points should be treated as they are, and
With the step of using the determination on which side of the curve the sample point should be treated as is when generating the rendered output.
The method according to any one of claims 1 to 4, further comprising. A method of generating rendered output using multiple input curves in a graphics processing system.
The method according to any one of claims 1 to 5 is carried out for each of the input curves.
Thereby, with respect to the array of transformed sample points in the standard space surrounding each of the plurality of standard curves, each of the plurality of standard curves in the standard space with respect to the array of transformed sample points. Steps to determine the sequence of the corresponding closest points on each, and
When generating a rendered output, the step of using the array of determined closest points on each of the plurality of standard curves with respect to the array of transformed sample points in the standard space.
Including methods. A graphics processing system for generating rendered output using input curves.
For the input curve defined in world space
Determine the portion of the standard curve defined in the standard space corresponding to the input curve and the transformations required to map the input curve to said portion of the standard curve.
For each of the plurality of sample points in the world space surrounding the input curve,
The sample point is transformed from the world space to the standard space using the determined transformation between the world space and the standard space.
The distance from the transformed sample point to the start and end points of the part of the standard curve is determined, and one of the start point or the end point is on the standard curve closest to the transformed sample point. By determining whether it is a point, a point on the determined portion of the standard curve closest to the transformed sample point in the standard space is determined.
Thereby, a processing circuit capable of determining the corresponding closest point on the standard curve in the standard space for each of the transformed sample points in the standard space surrounding the standard curve.
A processing circuit that can use the determined nearest point on the standard curve with respect to the transformed sample point in the standard space when generating the rendered output.
A graphics processing system. The graphics process according to claim 7 , wherein in order to determine the closest point on the standard curve, the processing circuit can minimize the distance from the transformed sample point to the standard curve. system. To determine the closest point on the standard curve, the processing circuit is between the transformed sample point and the point on the standard curve in the standard space closest to the transformed sample point. The graphics processing system according to claim 7 or 8 , wherein the distance can be determined. The graphics processing system according to claim 9 , wherein the processing circuit can store the determined distance from the sample point to the nearest point on the standard curve for each sample point. The processing circuit
For each of the plurality of sample points surrounding the curve, the closest determined point on the curve is used to determine on which side of the curve the sample points should be treated as is.
Thereby, for each of the sample points surrounding the curve, it is possible to determine on which side of the curve the sample points should be treated as they are.
The processing circuit can use the determination on which side of the curve the sample points should be treated as is when generating the rendered output.
The graphics processing system according to any one of claims 7 to 10. For each of the plurality of input curves defined in world space, to map a part of the standard curve defined in the standard space corresponding to the input curve and the input curve to the part of the standard curve. Determine the required conversion and
For each of the plurality of sample points in the world space surrounding the input curve,
The sample point is transformed from the world space to the standard space using the determined transformation between the world space and the standard space.
In the standard space, determine the point on the determined portion of the standard curve that is closest to the transformed sample point.
Thereby, with respect to the array of transformed sample points in the standard space surrounding each of the plurality of standard curves, each of the plurality of standard curves in the standard space with respect to the array of transformed sample points. Determine the sequence of the corresponding closest points on each,
A processing circuit that can use the array of determined closest points on each of the plurality of standard curves with respect to the array of transformed sample points in the standard space when generating the rendered output. With,
The graphics processing system according to any one of claims 7 to 11 , for generating a rendered output using a plurality of input curves. A method of generating graphics textures for use in a graphics processing system when generating rendered output using input curves.
For the input curve defined in world space
Determine the portion of the standard curve defined in the standard space corresponding to the input curve and the transformations required to map the input curve to said portion of the standard curve.
For each of the plurality of sample points in the world space surrounding the input curve,
The sample point is transformed from the world space to the standard space using the determined transformation between the world space and the standard space.
The distance from the transformed sample point to the start and end points of the part of the standard curve is determined, and one of the start point or the end point is on the standard curve closest to the transformed sample point. By determining whether it is a point, a point on the determined portion of the standard curve closest to the transformed sample point in the standard space is determined.
Thereby, with respect to each of the transformed sample points in the standard space surrounding the standard curve, a step of determining the corresponding closest point on the standard curve in the standard space.
For each of the sample points, a step of determining the distance from the sample point to the determined nearest point on the standard curve.
In the step of generating a graphics texture containing an array of texels, each texel corresponds to at least one of the sample points and for the at least one sample point from the at least one sample point. associated with the distance that is the determined to the standard curve, the steps,
Including methods. A device for generating graphics textures for use in graphics processing systems when generating rendered output using input curves.
For the input curve defined in world space
Determine the portion of the standard curve defined in the standard space corresponding to the input curve and the transformations required to map the input curve to said portion of the standard curve.
For each of the plurality of sample points in the world space surrounding the input curve,
The sample point is transformed from the world space to the standard space using the determined transformation between the world space and the standard space.
The distance from the transformed sample point to the start and end points of the part of the standard curve is determined, and one of the start point or the end point is on the standard curve closest to the transformed sample point. By determining whether it is a point, a point on the determined portion of the standard curve closest to the transformed sample point in the standard space is determined.
Thereby, for each of the transformed sample points in the standard space surrounding the standard curve, the corresponding closest points on the standard curve in the standard space are determined.
For each of the sample points, the distance from the sample point to the determined nearest point on the standard curve is determined.
It has a processing circuit that can generate graphics textures containing an array of texels.
Each texel corresponds to at least one of the sample points relative to the at least one sample point is associated from the at least one sample point in distance the determined to the standard curve,
apparatus. A computer-readable storage medium containing computer software code that performs the method according to any one of claims 1 to 6 , when executed in a data processing system.

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